Dual Radio Operation Between Access Systems Using 3GPP Radio Access Technology

ABSTRACT

Systems and methods of providing 5G access for a UE are generally described. The UE is simultaneously connected via dual radio operation to a legacy and 5G access system. The UE mobility management states for the access systems are independent of each other. The EPC and 5G CN share an HSS and may share a IP anchor. When handover occurs between access systems, the IP address is retained and the IP anchor used when the UE transmits an Attach Request having a Handover Attach Request Type and otherwise a new IP address is provided and the HSS but not the IP anchor is common between the access systems. The 5G eNB to which the UE is connected is standalone and connected to the 5G CN or dual mode and connected with an EPC via an LTE anchor in addition to the 5G CN.

PRIORITY CLAIM

This application claims the benefit of priority to U.S. ProvisionalPatent Application Ser. No. 62/238,064, filed, Oct. 6, 2015, andentitled “DUAL RADIO OPERATION BETWEEN ACCESS SYSTEMS USING 3GPP RADIOACCESS TECHNOLOGY,” which is incorporated herein by reference in itsentirety.

TECHNICAL FIELD

Embodiments pertain to radio access networks. Some embodiments relate tointeractions between different cellular and wireless local area network(WLAN) networks, including Third Generation Partnership Project LongTerm Evolution (3GPP LTE) networks and LTE advanced (LTE-A) networks aswell as 4^(th) generation (4G) networks and 5^(th) generation (5G)networks. Some embodiments relate to compatibility of 5G networks withnon-5G networks.

BACKGROUND

The use of communication devices, especially mobile communicationdevices, has continued to increase, in large part due to the increase inavailable applications and content such as gaming and video streaming.As a result, networks continue to develop, with the next generationwireless communication systems, such as the 4^(th) and 5^(th) generation(4G, 5G) systems, striving to improve access to information and datasharing. 5G in particular looks to provide a unified network/system thatis able to meet vastly different and sometime conflicting performancedimensions and services driven by disparate services and applicationswhile maintaining compatibility with legacy communication devices andapplications. Moreover, the incorporation of 5G systems into existingLTE/4G systems to enable seamless integration of the different systemsmay be undertaken in a number of ways.

BRIEF DESCRIPTION OF THE FIGURES

In the figures, which are not necessarily drawn to scale, like numeralsmay describe similar components in different views. Like numerals havingdifferent letter suffixes may represent different instances of similarcomponents. The figures illustrate generally, by way of example, but notby way of limitation, various embodiments discussed in the presentdocument.

FIG. 1 shows an example of a portion of an end-to-end networkarchitecture of a LTE network in accordance with some embodiments.

FIG. 2 illustrates components of a communication device in accordancewith some embodiments.

FIG. 3 illustrates a block diagram of a communication device inaccordance with some embodiments.

FIG. 4 illustrates another block diagram of a communication device inaccordance with some embodiments.

FIG. 5 illustrates a wireless communication system in accordance withsome embodiments.

FIG. 6 illustrates handover with IP address preservation in accordancewith some embodiments.

FIG. 7 illustrates a flow diagram of handover in accordance with someembodiments.

DETAILED DESCRIPTION

The following description and the drawings sufficiently illustratespecific embodiments to enable those skilled in the art to practicethem. Other embodiments may incorporate structural, logical, electrical,process, and other changes. Portions and features of some embodimentsmay be included in, or substituted for, those of other embodiments.Embodiments set forth in the claims encompass all available equivalentsof those claims.

FIG. 1 shows an example of a portion of an end-to-end networkarchitecture of a LTE network in accordance with some embodiments. Asused herein, an LTE network refers to both LTE and LTE Advanced (LTE-A)networks as well as other versions of LTE networks to be developed. Thenetwork 100 may comprise a radio access network (RAN) (e.g., asdepicted, the E-UTRAN or evolved universal terrestrial radio accessnetwork) 101 and core network 120 (e.g., shown as an evolved packet core(EPC)) coupled together through an S1 interface 115. For convenience andbrevity, only a portion of the core network 120, as well as the RAN 101,is shown in the example.

The core network 120 may include a mobility management entity (MME) 122,serving gateway (serving GW) 124, and packet data network gateway (PDNGW) 126. The RAN 101 may include evolved node Bs (eNBs) 104 (which mayoperate as base stations) for communicating with user equipment (UE)102. The cNBs 104 may include macro cNBs 104 a and low power (LP) eNBs104 b. Other elements, such as a Home Location Register (HLR)/HomeSubscriber Server (HSS), a database including subscriber information ofa 3GPP network that may perform configuration storage, identitymanagement and user state storage, and a Policy and Charging RuleFunction (PCRF) that performs policy decision for dynamically applyingQuality of Service (QoS) and charging policy per service flow, are notshown for convenience.

The MME 122 may be similar in function to the control plane of legacyServing GPRS Support Nodes (SGSN). The MME 122 may manage mobilityaspects in access such as gateway selection and tracking area listmanagement, performing both mobility management (MM) and sessionmanagement (SM). The Non-Access Stratum (NAS) is a part of the controlplane between a UE 102 and the MME 122. The NAS is used for signalingbetween the UE 102 and the EPC in the LTE/UMTS protocol stack. The NASsupports UE mobility and session management for establishing andmaintaining an IP connection between the UE 102 and PDN GW 126.

The serving GW 124 may terminate the user plane interface toward the RAN101, and route data packets between the RAN 101 and the core network120. In addition, the serving GW 124 may be a local mobility anchorpoint for inter-eNB handovers and also may provide an anchor forinter-3GPP mobility. Other responsibilities may include lawfulintercept, charging, and policy enforcement, packet routing, idle modepacket buffering, and triggering an MME to page a UE. The serving GW 124and the MME 122 may be implemented in one physical node or separatephysical nodes.

The PDN GW 126 may terminate a SGi interface toward the packet datanetwork (PDN). The PDN GW 126 may route data packets between the EPC 120and the external PDN, and may perform policy enforcement and chargingdata collection UE IP address assignment, packet screening andfiltering. The PDN GW 126 may also provide an anchor point for mobilitydevices with a non-LTE access. The external PDN can be any kind of IPnetwork, as well as an IP Multimedia Subsystem (IMS) domain. The PDN GW126 and the serving GW 124 may be implemented in a single physical nodeor separate physical nodes.

The eNBs 104 (macro and micro) may terminate the air interface protocoland may be the first point of contact for a UE 102. In some embodiments,an eNB 104 may fulfill various logical functions for the RAN 101including, but not limited to, RNC (radio network controller functions)such as radio bearer management, uplink and downlink dynamic radioresource management and data packet scheduling, and mobility managementIn accordance with embodiments, UEs 102 may be configured to communicateorthogonal frequency division multiplexed (OFDM) communication signalswith an eNB 104 over a multicarrier communication channel in accordancewith an OFDMA communication technique. The OFDM signals may comprise aplurality of orthogonal subcarriers.

The S1 interface 115 may be the interface that separates the RAN 101 andthe EPC 120. It may be split into two parts: the S1-U, which may carrytraffic data between the eNBs 104 and the serving GW 124, and the SI-MME, which may be a signaling interface between the eNBs 104 and theMME 122. The X2 interface may be the interface between eNBs 104. The X2interface may comprise two parts, the X2-C and X2-U The X2-C may be thecontrol plane interface between the eNBs 104, while the X2-U may be theuser plane interface between the eNBs 104.

With cellular networks, LP cells 104 b may be typically used to extendcoverage to indoor areas where outdoor signals do not reach well, or toadd network capacity in areas with dense usage. In particular, it may bedesirable to enhance the coverage of a wireless communication systemusing cells of different sizes, macrocells, microcells, picocells, andfemtocells, to boost system performance. The cells of different sizesmay operate on the same frequency band, or may operate on differentfrequency bands with each cell operating in a different frequency bandor only cells of different sizes operating on different frequency bands.As used herein, the term LP eNB refers to any suitable relatively LP eNBfor implementing a smaller cell (smaller than a macro cell) such as afemtocell, a picocell, or a microcell. Femtocell eNBs may be typicallyprovided by a mobile network operator to its residential or enterprisecustomers. A femtocell may be typically the size of a residentialgateway or smaller and generally connect to a broadband line. Thefemtocell may connect to the mobile operator's mobile network andprovide extra coverage in a range of typically 30 to 50 meters. Thus, aLP eNB 104 b might be a femtocell eNB. In some embodiments, when the LPeNB 104 b is a Home eNB (HeNB), a HeNB Gateway may be provided betweenthe HeNB and the MME/Scrvicc Gateway. This HeNB Gateway may controlmultiple HeNBs and provide user data and signal traffic from the HeNBstowards the MM/FService Gateway. Similarly, a picocell may be a wirelesscommunication system typically covering a small area, such asin-building (offices, shopping malls, train stations, etc.), or morerecently in-aircraft. A picocell eNB may generally connect through theX2 link to another eNB such as a macro eNB through its base stationcontroller (BSC) functionality and/or connect via an S1 interface to anMME/Service Gateway. Thus, LP eNB may be implemented with a picocell eNBsince it may be coupled to a macro eNB 104 a via an X2 interface.Picocell eNBs or other LP eNBs LP eNB 104 b may incorporate some or allfunctionality of a macro eNB LP eNB 104 a. In some cases, this may bereferred to as an access point base station or enterprise femtocell.

In general, the UE 102 may communicate with various types of systems,including a UTRAN and GERAN cell, which may provide voice services onlyor voice services and low data rate packet services, and an E-UTRANcell, which may provide packet services only or packet services andvoice/video services over packet transport. The UTRAN and GERAN cellsmay be coupled with a Serving General Packet Radio Subsystem SupportNode (SGSN) and mobile switching center (MSC) server. The E-UTRAN may becoupled with the MME 122, which in turn may be coupled with the SGSN andthe MSC server. The GERAN and UTRAN RANs may be connected to acircuit-switched (CS) domain of the network 100. For circumstances inwhich UE 102 is communicating via the E-UTRAN cell when setup of a CSvoice call is desired, the mobile network may include a CS fallback(CSFB). In CSFB, the UE 102 in the E-UTRAN cell may engage in a CScall—either by setting up a call or responding to a paging message for aCS call. The network 100 may redirect the UE 102 to a GERAN or UTRANcell, such as via a packet-switched (PS) handover, via a “release withredirection” procedure, or via a network-assisted cell change over(CCO). In such examples, the UE 102 can set up the mobile originatingcall or receive the mobile terminating call via the MSC server. Once theCS call is released in GERAN and/or UTRAN cells, the UE 102 may returnto the E-UTRAN cell either on its own (e.g., via cell re-selection) orwith the help of the GERAN and/or UTRAN (e.g., if, during the release ofthe radio connection for the CS call the GERAN and/or UTRAN cellscommands the UE 102 to immediately select a specific E-UTRAN cell).

In operation, for example during the CS call, if the UE 102 is in aGERAN cell and either does not support the simultaneous use of CSservices and packet services, the network 100 may suspend packetservices for the UE 102. Downlink packets may not be delivered to the UE102 but may be forwarded by the PDN GW 126 towards the UE 102. In anexample, the UE 102 and/or one of the core network nodes (e.g., the MMEand/or the SGSN, as appropriate) may inform the serving GW 124 and/orthe PDN GW 126 that the gateways should no longer forward downlink userpackets from the UE 102. The MME 122 or SGSN may also deactivatededicated packet bearers which are used for real-time services. The CScall may be released or during the CS call the UE 102 may be handed overto a cell where CS services and packet services can be usedsimultaneously. Packet services may then be resumed.

FIG. 2 illustrates components of a communication device in accordancewith some embodiments. The communication device 200 may be a UE, eNB orother network component as described herein. The communication device200 may be a stationary, non-mobile device or may be a mobile device. Insome embodiments, the UE 200 may include application circuitry 202,baseband circuitry 204. Radio Frequency (RF) circuitry 206, front-endmodule (FEM) circuitry 208 and one or more antennas 210, coupledtogether at least as shown. At least some of the baseband circuitry 204,RF circuitry 206, and FEM circuitry 208 may form a transceiver. In someembodiments, other network elements, such as the MME may contain some orall of the components shown in FIG. 2.

The application or processing circuitry 202 may include one or moreapplication processors. For example, the application circuitry 202 mayinclude circuitry such as, but not limited to, one or more single-coreor multi-core processors. The processor(s) may include any combinationof general-purpose processors and dedicated processors (e.g., graphicsprocessors, application processors, etc.). The processors may be coupledwith and/or may include memory/storage and may be configured to executeinstructions stored in the memory/storage to enable various applicationsand/or operating systems to run on the system.

The baseband circuitry 204 may include circuitry such as, but notlimited to, one or more single-core or multi-core processors. Thebaseband circuitry 204 may include one or more baseband processorsand/or control logic to process baseband signals received from a receivesignal path of the RF circuitry 206 and to generate baseband signals fora transmit signal path of the RF circuitry 206. Baseband processingcircuitry 204 may interface with the application circuitry 202 forgeneration and processing of the baseband signals and for controllingoperations of the RF circuitry 206. For example, in some embodiments,the baseband circuitry 204 may include a second generation (2G) basebandprocessor 204 a, third generation (3G) baseband processor 204 b, fourthgeneration (4G) baseband processor 204 c, and/or other basebandprocessor(s) 204 d for other existing generations, generations indevelopment or to be developed in the future (e.g., fifth generation(5G), 5G, etc.). The baseband circuitry 204 (e.g., one or more ofbaseband processors 204 a-d) may handle various radio control functionsthat enable communication with one or more radio networks via the RFcircuitry 206. The radio control functions may include, but are notlimited to, signal modulation/demodulation, encoding/decoding, radiofrequency shifting, etc. In some embodiments, modulation/demodulationcircuitry of the baseband circuitry 204 may include FFT, precoding,and/or constellation mapping/demapping functionality. In someembodiments, encoding/decoding circuitry of the baseband circuitry 204may include convolution, tail-biting convolution, turbo, Viterbi, and/orLow Density Parity Check (LDPC) encoder/decoder functionality.Embodiments of modulation/demodulation and encoder/decoder functionalityare not limited to these examples and may include other suitablefunctionality in other embodiments.

In some embodiments, the baseband circuitry 204 may include elements ofa protocol stack such as, for example, elements of an Evolved UTRON(EUTRAN) protocol including, for example, physical (PHY), media accesscontrol (MAC), radio link control (RLC), packet data convergenceprotocol (PDCP), radio resource control (RRC) elements, and/orNon-Access Stratum (NAS) elements. A central processing unit (CPU) 204 cof the baseband circuitry 204 may be configured to run elements of theprotocol stack for signaling of the PHY, MAC, RLC, PDCP and/or RRClayers, and/or NAS. In some embodiments, the baseband circuitry mayinclude one or more audio digital signal processor(s) (DSP) 204 f. Theaudio DSP(s) 204 f may be include elements for compression/decompressionand echo cancellation and may include other suitable processing elementsin other embodiments. Components of the baseband circuitry may besuitably combined in a single chip, a single chipset, or disposed on asame circuit board in some embodiments. In some embodiments, some or allof the constituent components of the baseband circuitry 204 and theapplication circuitry 202 may be implemented together such as, forexample, on a system on a chip (SOC).

In some embodiments, the baseband circuitry 204 may provide forcommunication compatible with one or more radio technologies. Forexample, in some embodiments, the baseband circuitry 204 may supportcommunication with an EUTRAN and/or other wireless metropolitan areanetworks (WMAN), a wireless local area network (WLAN), a wirelesspersonal area network (WPAN). Embodiments in which the basebandcircuitry 204 is configured to support radio communications of more thanone wireless protocol may be referred to as multi-mode basebandcircuitry. In some embodiments, the device can be configured to operatein accordance with communication standards or other protocols orstandards, including Institute of Electrical and Electronic Engineers(IEEE) 802.16 wireless technology (WiMax), IEEE 802.11 wirelesstechnology (WiFi) including IEEE 802.11 ad, which operates in the 60 GHzmillimeter wave spectrum, various other wireless technologies such asglobal system for mobile communications (GSM), enhanced data rates forGSM evolution (EDGE), GSM EDGE radio access network (GERAN), universalmobile telecommunications system (UNITS), UMTS terrestrial radio accessnetwork (UTRAN), or other 2G, 3G, 4G, 5G, etc. technologies eitheralready developed or to be developed.

RF circuitry 206 may enable communication with wireless networks usingmodulated electromagnetic radiation through a non-solid medium. Invarious embodiments, the RF circuitry 206 may include switches, filters,amplifiers, etc. to facilitate the communication with the wirelessnetwork. RF circuitry 206 may include a receive signal path which mayinclude circuitry to down-convert RF signals received from the FEMcircuitry 208 and provide baseband signals to the baseband circuitry204. RF circuitry 206 may also include a transmit signal path which mayinclude circuitry to up-convert baseband signals provided by thebaseband circuitry 204 and provide RF output signals to the FEMcircuitry 208 for transmission.

In some embodiments, the RF circuitry 206 may include a receive signalpath and a transmit signal path. The receive signal path of the RFcircuitry 206 may include mixer circuitry 206 a, amplifier circuitry 206b and filter circuitry 206 c. The transmit signal path of the RFcircuitry 206 may include filter circuitry 206 c and mixer circuitry 206a. RF circuitry 206 may also include synthesizer circuitry 206 d forsynthesizing a frequency for use by the mixer circuitry 206 a of thereceive signal path and the transmit signal path In some embodiments,the mixer circuitry 206 a of the receive signal path may be configuredto down-convert RF signals received from the FEM circuitry 208 based onthe synthesized frequency provided by synthesizer circuitry 206 d. Theamplifier circuitry 206 b may be configured to amplify thedown-converted signals and the filter circuitry 206 c may be a low-passfilter (LPF) or band-pass filter (BPF) configured to remove unwantedsignals from the down-converted signals to generate output basebandsignals. Output baseband signals may be provided to the basebandcircuitry 204 for further processing. In some embodiments, the outputbaseband signals may be zero-frequency baseband signals, although thisis not a requirement. In some embodiments, mixer circuitry 206 a of thereceive signal path may comprise passive mixers, although the scope ofthe embodiments is not limited in this respect.

In some embodiments, the mixer circuitry 206 a of the transmit signalpath may be configured to up-convert input baseband signals based on thesynthesized frequency provided by the synthesizer circuitry 206 d togenerate RF output signals for the FEM circuitry 208. The basebandsignals may be provided by the baseband circuitry 204 and may befiltered by filter circuitry 206 c. The filter circuitry 206 c mayinclude a low-pass filter (LPF), although the scope of the embodimentsis not limited in this respect.

In some embodiments, the mixer circuitry 206 a of the receive signalpath and the mixer circuitry 206 a of the transmit signal path mayinclude two or more mixers and may be arranged for quadraturedownconversion and/or upconversion respectively. In some embodiments,the mixer circuitry 206 a of the receive signal path and the mixercircuitry 206 a of the transmit signal path may include two or moremixers and may be arranged for image rejection (e.g., Hartley imagerejection). In some embodiments, the mixer circuitry 206 a of thereceive signal path and the mixer circuitry 206 a may be arranged fordirect downconversion and/or direct upconversion, respectively. In someembodiments, the mixer circuitry 206 a of the receive signal path andthe mixer circuitry 206 a of the transmit signal path may be configuredfor super-heterodyne operation.

In some embodiments, the output baseband signals and the input basebandsignals may be analog baseband signals, although the scope of theembodiments is not limited in this respect In some alternateembodiments, the output baseband signals and the input baseband signalsmay be digital baseband signals. In these alternate embodiments, the RFcircuitry 206 may include analog-to-digital converter (ADC) anddigital-to-analog converter (DAC) circuitry and the baseband circuitry204 may include a digital baseband interface to communicate with the RFcircuitry 206.

In some dual-mode embodiments, a separate radio IC circuitry may beprovided for processing signals for each spectrum, although the scope ofthe embodiments is not limited in this respect.

In some embodiments, the synthesizer circuitry 206 d may be afractional-N synthesizer or a fractional N/N+1 synthesizer, although thescope of the embodiments is not limited in this respect as other typesof frequency synthesizers may be suitable. For example, synthesizercircuitry 206 d may be a delta-sigma synthesizer, a frequencymultiplier, or a synthesizer comprising a phase-locked loop with afrequency divider.

The synthesizer circuitry 206 d may be configured to synthesize anoutput frequency for use by the mixer circuitry 206 a of the RFcircuitry 206 based on a frequency input and a divider control input. Insome embodiments, the synthesizer circuitry 206 d may be a fractionalN/N+1 synthesizer.

In some embodiments, frequency input may be provided by a voltagecontrolled oscillator (VCO), although that is not a requirement. Dividercontrol input may be provided by either the baseband circuitry 204 orthe applications processor 202 depending on the desired output frequencyIn some embodiments, a divider control input (e.g., N) may be determinedfrom a look-up table based on a channel indicated by the applicationsprocessor 202.

Synthesizer circuitry 206 d of the RF circuitry 206 may include adivider, a delay-locked loop (DLL), a multiplexer and a phaseaccumulator. In some embodiments, the divider may be a dual modulusdivider (DMD) and the phase accumulator may be a digital phaseaccumulator (DPA). In some embodiments, the DMD may be configured todivide the input signal by either N or N+1 (e.g., based on a carry out)to provide a fractional division ratio. In some example embodiments, theDLL may include a set of cascaded, tunable, delay elements, a phasedetector, a charge pump and a D-type flip-flop. In these embodiments,the delay elements may be configured to break a VCO period up into Ndequal packets of phase, where Nd is the number of delay elements in thedelay line. In this way, the DLL provides negative feedback to helpensure that the total delay through the delay line is one VCO cycle.

In some embodiments, synthesizer circuitry 206 d may be configured togenerate a carrier frequency as the output frequency, while in otherembodiments, the output frequency may be a multiple of the carrierfrequency (e.g., twice the carrier frequency, four times the carrierfrequency) and used in conjunction with quadrature generator and dividercircuitry to generate multiple signals at the carrier frequency withmultiple different phases with respect to each other. In someembodiments, the output frequency may be a LO frequency (f_(LO)). Insome embodiments, the RF circuitry 206 may include an IQ/polarconverter.

FEM circuitry 208 may include a receive signal path which may includecircuitry configured to operate on RF signals received from one or moreantennas 210, amplify the received signals and provide the amplifiedversions of the received signals to the RF circuitry 206 for furtherprocessing. FEM circuitry 208 may also include a transmit signal pathwhich may include circuitry configured to amplify signals fortransmission provided by the RF circuitry 206 for transmission by one ormore of the one or more antennas 210.

In some embodiments, the FEM circuitry 208 may include a TX/RX switch toswitch between transmit mode and receive mode operation. The FEMcircuitry may include a receive signal path and a transmit signal path.The receive signal path of the FEM circuitry may include a low-noiseamplifier (LNA) to amplify received RF signals and provide the amplifiedreceived RF signals as an output (e.g., to the RF circuitry 206). Thetransmit signal path of the FEM circuitry 208 may include a poweramplifier (PA) to amplify input RF signals (e.g., provided by RFcircuitry 206), and one or more filters to generate RF signals forsubsequent transmission (e.g., by one or more of the one or moreantennas 210.

In some embodiments, the communication device 200 may include additionalelements such as, for example, memory/storage, display, camera, sensor,and/or input/output (I/O) interface as described in more detail below.In some embodiments, the communication device 200 described herein maybe part of a portable wireless communication device, such as a personaldigital assistant (PDA), a laptop or portable computer with wirelesscommunication capability, a web tablet, a wireless telephone, asmartphone, a wireless headset, a pager, an instant messaging device, adigital camera, an access point, a television, a medical device (e.g., aheart rate monitor, a blood pressure monitor, etc.), or other devicethat may receive and/or transmit information wirelessly. In someembodiments, the communication device 200 may include one or more userinterfaces designed to enable user interaction with the system and/orperipheral component interfaces designed to enable peripheral componentinteraction with the system. For example, the communication device 200may include one or more of a keyboard, a keypad, a touchpad, a display,a sensor, a non-volatile memory port, a universal serial bus (USB) port,an audio jack, a power supply interface, one or more antennas, agraphics processor, an application processor, a speaker, a microphone,and other I/O components. The display may be an LCD or LED screenincluding a touch screen. The sensor may include a gyro sensor, anaccelerometer, a proximity sensor, an ambient light sensor, and apositioning unit. The positioning unit may communicate with componentsof a positioning network, e.g., a global positioning system (GPS)satellite.

The antennas 210 may comprise one or more directional or omnidirectionalantennas, including, for example, dipole antennas, monopole antennas,patch antennas, loop antennas, microstrip antennas or other types ofantennas suitable for transmission of RF signals. In some multiple-inputmultiple-output (MIMO) embodiments, the antennas 210 may be effectivelyseparated to take advantage of spatial diversity and the differentchannel characteristics that may result.

Although the communication device 200 is illustrated as having severalseparate functional elements, one or more of the functional elements maybe combined and may be implemented by combinations ofsoftware-configured elements, such as processing elements includingdigital signal processors (DSPs), and/or other hardware elements. Forexample, some elements may comprise one or more microprocessors, DSPs,field-programmable gate arrays (FPGAs), application specific integratedcircuits (ASICs), radio-frequency integrated circuits (RFICs) andcombinations of various hardware and logic circuitry for performing atleast the functions described herein. In some embodiments, thefunctional elements may refer to one or more processes operating on oneor more processing elements.

Embodiments may be implemented in one or a combination of hardware,firmware and software. Embodiments may also be implemented asinstructions stored on a computer-readable storage device, which may beread and executed by at least one processor to perform the operationsdescribed herein. A computer-readable storage device may include anynon-transitory mechanism for storing information in a form readable by amachine (e.g., a computer). For example, a computer-readable storagedevice may include read-only memory (ROM), random-access memory (RAM),magnetic disk storage media, optical storage media, flash-memorydevices, and other storage devices and media. Some embodiments mayinclude one or more processors and may be configured with instructionsstored on a computer-readable storage device.

FIG. 3 is a block diagram of a communication device in accordance withsome embodiments. The device may be a UE, for example, such as the UEshown in FIG. 1. The physical layer circuitry 302 may perform variousencoding and decoding functions that may include formation of basebandsignals for transmission and decoding of received signals. Thecommunication device 300 may also include medium access control layer(MAC) circuitry 304 for controlling access to the wireless medium. Thecommunication device 300 may also include processing circuitry 306, suchas one or more single-core or multi-core processors, and memory 308arranged to perform the operations described herein. The physical layercircuitry 302, MAC circuitry 304 and processing circuitry 306 may handlevarious radio control functions that enable communication with one ormore radio networks compatible with one or more radio technologies. Theradio control functions may include signal modulation, encoding,decoding, radio frequency shifting, etc. For example, similar to thedevice shown in FIG. 2, in some embodiments, communication may beenabled with one or more of a WMAN, a WLAN, and a WPAN. In someembodiments, the communication device 300 can be configured to operatein accordance with 3GPP standards or other protocols or 30 o standards,including WiMax. WiFi, WiGig, GSM, EDGE, GERAN. UMTS, UTRAN, or other3G, 3G, 4G, 5G, etc. technologies either already developed or to bedeveloped. The communication device 300 may include transceivercircuitry 312 to enable communication with other external deviceswirelessly and interfaces 314 to enable wired communication with otherexternal devices. As another example, the transceiver circuitry 312 mayperform various transmission and reception functions such as conversionof signals between a baseband range and a Radio Frequency (RF) range.

The antennas 301 may comprise one or more directional or omnidirectionalantennas, including, for example, dipole antennas, monopole antennas,patch antennas, loop antennas, microstrip antennas or other types ofantennas suitable for transmission of RF signals. In some MIMOembodiments, the antennas 301 may be effectively separated to takeadvantage of spatial diversity and the different channel characteristicsthat may result.

Although the communication device 300 is illustrated as having severalseparate functional elements, one or more of the functional elements maybe combined and may be implemented by combinations ofsoftware-configured elements, such as processing elements includingDSPs, and/or other hardware elements. For example, some elements maycomprise one or more microprocessors, DSPs, FPGAs, ASICs, RFICs andcombinations of various hardware and logic circuitry for performing atleast the functions described herein. In some embodiments, thefunctional elements may refer to one or more processes operating on oneor more processing elements. Embodiments may be implemented in one or acombination of hardware, firmware and software. Embodiments may also beimplemented as instructions stored on a computer-readable storagedevice, which may be read and executed by at least one processor toperform the operations described herein.

FIG. 4 illustrates another block diagram of a communication device inaccordance with some embodiments. In alternative embodiments, thecommunication device 400 may operate as a standalone device or may beconnected (e.g., networked) to other communication devices. In anetworked deployment, the communication device 400 may operate in thecapacity of a server communication device, a client communicationdevice, or both in server-client network environments. In an example,the communication device 400 may act as a peer communication device inpeer-to-peer (P2P) (or other distributed) network environment. Thecommunication device 400 may be a UE, eNB, PC, a tablet PC, a STB, aPDA, a mobile telephone, a smart phone, a web appliance, a networkrouter, switch or bridge, or any communication device capable ofexecuting instructions (sequential or otherwise) that specify actions tobe taken by that communication device. Further, while only a singlecommunication device is illustrated, the term “communication device”shall also be taken to include any collection of communication devicesthat individually or jointly execute a set (or multiple sets) ofinstructions to perform any one or more of the methodologies discussedherein, such as cloud computing, software as a service (SaaS), othercomputer cluster configurations.

Examples, as described herein, may include, or may operate on, logic ora number of components, modules, or mechanisms. Modules are tangibleentities (e.g., hardware) capable of performing specified operations andmay be configured or arranged in a certain manner. In an example,circuits may be arranged (e.g., internally or with respect to externalentities such as other circuits) in a specified manner as a module. Inan example, the whole or part of one or more computer systems (e.g., astandalone, client or server computer system) or one or more hardwareprocessors may be configured by firmware or software (e.g.,instructions, an application portion, or an application) as a modulethat operates to perform specified operations. In an example, thesoftware may reside on a communication device readable medium. In anexample, the software, when executed by the underlying hardware of themodule, causes the hardware to perform the specified operations.

Accordingly, the term “module” is understood to encompass a tangibleentity, be that an entity that is physically constructed, specificallyconfigured (e.g., hardwired), or temporarily (e.g., transitorily)configured (e.g., programmed) to operate in a specified manner or toperform part or all of any operation described herein. Consideringexamples in which modules are temporarily configured, each of themodules need not be instantiated at any one moment in time. For example,where the modules comprise a general-purpose hardware processorconfigured using software, the general-purpose hardware processor may beconfigured as respective different modules at different times. Softwaremay accordingly configure a hardware processor, for example, toconstitute a particular module at one instance of time and to constitutea different module at a different instance of time.

Communication device (e.g., computer system) 400 may include a hardwareprocessor 402 (e.g., a central processing unit (CPU), a graphicsprocessing unit (GPU), a hardware processor core, or any combinationthereof), a main memory 404 and a static memory 406, some or all ofwhich may communicate with each other via an interlink (e.g., bus) 408.The communication device 400 may further include a display unit 410, analphanumeric input device 412 (e.g., a keyboard), and a user interface(UI) navigation device 414 (e.g., a mouse). In an example, the displayunit 410, input device 412 and UI navigation device 414 may be a touchscreen display. The communication device 400 may additionally include astorage device (e.g., drive unit) 416, a signal generation device 418(e.g., a speaker), a network interface device 420, and one or moresensors 421, such as a global positioning system (GPS) sensor, compass,accelerometer, or other sensor. The communication device 400 may includean output controller 428, such as a serial (e.g., universal serial bus(USB), parallel, or other wired or wireless (e.g., infrared (IR), nearfield communication (NFC), etc.) connection to communicate or controlone or more peripheral devices (e.g., a printer, card reader, etc.).

The storage device 416 may include a communication device readablemedium 422 on which is stored one or more sets of data structures orinstructions 424 (e.g., software) embodying or utilized by any one ormore of the techniques or functions described herein. The instructions424 may also reside, completely or at least partially, within the mainmemory 404, within static memory 406, or within the hardware processor402 during execution thereof by the communication device 400. In anexample, one or any combination of the hardware processor 402, the mainmemory 404, the static memory 406, or the storage device 416 mayconstitute communication device readable media.

While the communication device readable medium 422 is illustrated as asingle medium, the term “communication device readable medium” mayinclude a single medium or multiple media (e.g., a centralized ordistributed database, and/or associated caches and servers) configuredto store the one or more instructions 424.

The term “communication device readable medium” may include any mediumthat is capable of storing, encoding, or carrying instructions forexecution by the communication device 400 and that cause thecommunication device 400 to perform any one or more of the techniques ofthe present disclosure, or that is capable of storing, encoding orcarrying data structures used by or associated with such instructions.Non-limiting communication device readable medium examples may includesolid-state memories, and optical and magnetic media. Specific examplesof communication device readable media may include: non-volatile memory,such as semiconductor memory devices (e.g., Electrically ProgrammableRead-Only Memory (EPROM). Electrically Erasable Programmable Read-OnlyMemory (EEPROM)) and flash memory devices; magnetic disks, such asinternal hard disks and removable disks; magneto-optical disks: RandomAccess Memory (RAM); and CD-ROM and DVD-ROM disks. In some examples,communication device readable media may include non-transitorycommunication device readable media. In some examples, communicationdevice readable media may include communication device readable mediathat is not a transitory propagating signal.

The instructions 424 may further be transmitted or received over acommunications network 426 using a transmission medium via the networkinterface device 420 utilizing any one of a number of transfer protocols(e.g., frame relay, internet protocol (IP), transmission controlprotocol (TCP), user datagram protocol (UDP), hypertext transferprotocol (HTTP), etc.). Example communication networks may include alocal area network (LAN), a wide area network (WAN), a packet datanetwork (e.g., the Internet), mobile telephone networks (e.g., cellularnetworks), Plain Old Telephone (POTS) networks, and wireless datanetworks (e.g., IEEE 802.11 family of standards known as WiFi®, IEEE802.16 family of standards known as WiMax®), IEEE 802.15.4 family ofstandards, a LTE family of standards, a UMTS family of standards,peer-to-peer (P2P) networks, among others. In an example, the networkinterface device 420 may include one or more physical jacks (e.g.,Ethernet, coaxial, or phone jacks) or one or more antennas to connect tothe communications network 426. In an example, the network interfacedevice 420 may include a plurality of antennas to wirelessly communicateusing at least one of single-input multiple-output (SIMO), MIMO, ormultiple-input single-output (MISO) techniques. In some examples, thenetwork interface device 420 may wirelessly communicate using MultipleUser MIMO techniques. The term “transmission medium” shall be taken toinclude any intangible medium that is capable of storing, encoding orcarrying instructions for execution by the communication device 400, andincludes digital or analog communications signals or other intangiblemedium to facilitate communication of such software.

To support the coming connectivity needs, standardization of nextgeneration (5G) cellular technology is currently under discussion. Oneor more new radio access technologies (RATs) have yet to be defined. Theaddition of 5G systems to the 4G systems described above may involveseveral phases to enable the various user and network goals to beachieved. For example, considering mobile broadband, one desire is toprovide a substantially uniform user experience independent of the typeof UE, amount of network traffic, radio access technology used, etc. Tothis end, the waveforms and frame structure used by 5G systems, as wellas the inter and intra-RAT interconnectivity with existing 4G andearlier systems, may be standardized. For example, some of the issueswith 5G systems to be standardized include the use of additionalspectrum, including ultra-high frequencies of up to about 100 GHz and ofthe unlicensed band, as well as the use of advanced techniques such asmulti-site MIMO, beamforming and scalable bandwidths.

At present, two phases may be used in implementation of 5G systems.Phase 1 of implementation of the 5G system may be to address an initialsubset of the International Mobile Telecommunication (IMT)-2020requirements, while Phase 2 addresses the remaining requirements. Phase1 may introduce a new RAT that is not backwards compatible to LTE andmay be specifically optimized for enhanced mobile broadband (eMBB) Phase1 may support a wider spectrum range than present LTE systems, up toabout 30-40 GHz, and use both time and frequency division duplexing(TDD, FDD). Phase 2 may be optimized for all 5G use cases and maysupport a frequency range of between about 0.3 and 100 GHz usingflexible TDD and FDD frame structures.

FIG. 5 illustrates a wireless communication system in accordance withsome embodiments. The system 500 of FIG. 5 illustrates one embodiment ofa Phase 1 system 510 and Phase 2 deployment with Phase 1 and Phase 2 UEs502 a, 502 b being disposed in cells of each type. In particular, Phase1 deployment 500 may focus on a non-standalone 5G RAT cell 516 operatingin Dual Connectivity (DC) mode as a booster cell controlled by anLTE-based anchor cell 514 through an X2 interface. The 5G booster cell516 may provide additional capacity within a predetermined area insidean anchor cell 514, which may employ a different RAT than the boostercell. The 5G booster cell 516 may only communicate with the LTE anchorcell 514 in Phase 1. The LTE anchor cell 514 and 5G booster cell 516 maybe used, for example, in a Coordinated Multipoint (CoMP) system.

In downlink CoMP, the anchor and booster cells 514, 516 may provideoverlapping coverage and may coordinate transmissions to a Phase 1 orPhase 2 UE 502 a. 502 b. In uplink CoMP, the reception of UE signals maybe coordinated among the cells 514, 516 to improve network performanceat cell edges. The cells 514, 516 providing the overlapping coverage maybe a homogeneous set of macro cells or may be heterogeneous, including amacro anchor cell and a LP booster 5G cell. The cells 514, 516 may begeographically separated but dynamically coordinated through ahigh-speed backhaul to provide joint scheduling and transmissions aswell as proving joint processing of the received signals. CoMP may usedifferent techniques, which include Joint Processing, Dynamic PointSelection and Coordinated scheduling/beamforming. In Joint Processing,the cells 514, 516 may transmit data on the same frequency in the samesubframe and/or uplink transmissions from the Phase 1 or Phase 2 UE 502a, 502 b may be received by the cells 514, 516 and combined to improvethe signal quality and strength and perhaps actively cancel interferencefrom transmissions that are intended for other UEs. This may increasethe amount of data in the network dependent upon how many cells transmitthe data. Uplink transmissions from the Phase 1 or Phase 2 UE 502 a, 502b may be detected by antennas at the different cells 514, 516, which mayform a virtual antenna array. The signals received by the cells 514, 516may be combined and processed to increase the strength of low strengthsignals or those masked by interference. In Dynamic Point Selection,data may available for transmission at multiple cells 514, 516 but onlyscheduled from cells 514, 516 in each subframe. In Coordinatedscheduling/beamforming, each cell 514, 516 in the CoMP area may transmitdata to the UE in different subframes while scheduling decisions as wellas beam coordination are coordinated among the cells 514, 516. In someembodiments, blanking or muting of signals from one cells 514, 516 maybe used when another cell 514, 516 is transmitting to decreaseinterference.

The LTE anchor cell 514 (and thus 5G booster cell 516) may be connectedwith an LTE core network (EPC) 512 through an S1 interface similar tothe system shown in FIG. 1. The EPC 512 may be connected with the HSS504 through an S6a interface and with the PGW 506 through an S5interface. The PGW 506 may serve as an IP anchor for the Phase 1 orPhase 2 UE 502 a, 502 b. By anchoring the 5G booster cell 516 at an LTEanchor 514, the EPC 512 may perceive only the LTE cell 514, therebyallowing both cells 514, 516 to be supported with the legacy EPC network512 with minimal or no changes.

In some embodiments of a Phase 1 deployment, a 5G standalone cell 530may be present in addition to the 5G booster cell 516. In other Phase 1embodiments, the 5G standalone cell 530 may not be present—instead beinga Phase 2 deployment. The 5G standalone cell 530 may be connected via a5G S1 interface with a new 5G core network 540. The 5G core network 540may be connected with the HSS 504 through an interface, which may be thesame as the S6a interface between the LTE EPC 512 and the HSS 504 or maybe a 5G S6a interface that differs from the S6a interface between theLTE EPC 512 and the HSS 504. Connection between the LTE EPC 512 and the5G core network 540 may be limited in some embodiments to HSS 504access. The 5G core network 540 in certain embodiments may be connectedwith an IP anchor function equivalent to the PGW 506 through a 5G S5interface.

A Phase 2 deployment is also depicted in FIG. 5. In Phase 2, both a 5Gnon-standalone (dual mode) cell 520 and the 5G standalone cell 530 maybe connected with the 5G core network 540 via a 5G S1 interface. The 5Gnon-standalone cell 520 may be additionally connected with the LTEanchor cell 514 through an X2 interface. Phase 1 or 2 may defineprovisions for the standalone 5G RAT cell 530 that connects to the 5Gcore network 540. The 5G non-standalone cell 520 may be upgraded tosupport dual mode operation. In dual mode, the 5G non-standalone cell520 may act as a booster cell to the LTE anchor 514 through the X2interface with connection to the EPC 512, or may act as a stand-alonecell connected to the new 5G core network 514 through the 5G S1interface.

Phase 1 UEs 502 a may be steered to the 5G booster mode cell 516 or to aplain LTE cell, such as the LTE anchor cell 514. Phase 2 dual mode cells520 may, on the other hand, be capable of supporting both booster andstandalone mode of operation. The booster mode may be used for Phase 2UEs 502 b only when the Phase 2 UEs 502 b are in coverage of a 5Gbooster cell that has not been upgraded for dual-mode operation. The LTEanchor 514 may be upgraded to steer communications of Phase 2 UEs 502 bto the 5G core network 540 through a 5G S1 interface and of legacy UEs502 a to the EPC 512. If the LTE anchor 514 is not upgraded,communications of all of the Phase 1 or Phase 2 UE 502 a. 502 b may bedirected to the EPC 512. The LTE anchor 514 may support the LTE-Uuinterface independent of whether or not the LTE anchor 514 is able tocommunicate with the 5G core network 540. Phase 2 UEs may containmultiple radios (including transmit/receive chains and other circuitry)that are configured to communicate using the different RATs, e.g. forLTE and 5G communications.

In some embodiments, the 5G core network 540 may permit servicecontinuity when the Phase 1 or Phase 2 UE 502 a, 502 b moves between thePhase 1 and Phase 2 networks, or between Phase 2 and other legacynetworks, such as EPS networks with 2G, 3G or LTE access. The 5G corenetwork 540 may, however, carry little to none of the baggage of thelegacy LTE core network 512. The use of a dual radio operation in thePhase 1 or Phase 2 UE 502 a, 502 b may facilitate interworking betweenthe legacy 4G access system (i.e., radio access network andcorresponding Core Network) and the 5G generation access system byminimizing the legacy baggage carried over to the 5G generation system,while still allowing for service continuity as UE moves from one accesssystem to another In the dual radio operation, both access systems mayrely on a 3GPP RAT but may have significantly different packet corenetworks. The legacy side of the access system may thus be composed ofthe 3GPP EPC network 512 and one of the following 3GPP RATs: 2G/GPRS,3G/UMTS, 4G/LTE or LTE-anchored 5G booster cell operating in DualConnectivity (DC) mode; the 5G side the access system may be composed ofthe 5G core network 540 and the standalone 5G cell 530. As above, theLTE anchor cell 514 may be upgraded to support the 5G core network-RANinterface towards the 5G core network 540 or the system 500 may operateusing dual radio operation.

When the EPS was defined by 3GPP in the Release 8 specifications,interworking between the 3GPP-defined RATs (2G/GPRS, 3G/UMTS, 4G/LTE)was assumed of the single radio type. This is to say that at any pointin time a single radio UE may be connected to only one RAT type. Incontrast, interworking with EPC-connected non-3GPP radio accesstechnologies (e.g., WLAN) also allows for dual radio operation where theUE can simultaneously be connected to both a 3GPP RAT (i.e., to the EPCvia an LTE cell) and to a WLAN (i.e., via an EPC-connected WLAN). Onebenefit of dual radio operation is that it allows for loose couplingbetween the two access systems, in that each access system can have itsown authentication, mobility management, PDN connection model, sessionmanagement, QoS and bearer schemes, while still allowing for IP addresscontinuity when UE moves traffic from one access system to the other.The different access systems may perform independent mobility managementmechanisms. For instance, the UE can be in Connected mode in one accesssystem, while being Idle mode in the other access system.

As shown in FIG. 5, the dual radio interworking may also be used betweentwo access systems both of which are based on a 3GPP RAT, e.g. betweenEPC-connected 3GPP RATs and New 5G CN-connected 3GPP RATs. Theconvergence point between the two access systems that are interworked indual radio mode may be limited to only the HSS 504. In otherembodiments, another convergence point may be the PGW 506. As above, thePGW (or PDN GW) may route data packets between the EPC 512 and anexternal PDN for an EPC-attached UE or between the 5G core network 540and that same external PDN for a 5G CN-attached UE. The HSS 504 maystore the user subscription data that is common for all accesses.

In some embodiments, it may be desirable to preserve the IP address whenhanding over between the legacy network and the 5G network; in otherembodiments an entirely new IP address may be used when handover occursbetween the networks. In some embodiments, a common PGW 506 may be usedonly in cases in which IP address preservation is used when traffic ismoved from one access system to another. Whether or not IP addresspreservation is desirable may depend on the applications operating. Inparticular, a number of currently available applications may be capableof surviving IP address changes without breaking the session. Suchapplications include, for example, SIP-based applications, DynamicAdaptive Streaming over HTTP (DASH), or transport protocols (e.g.,MultiPath TCP). While these applications are presently in the minority,the number of applications that have the capability to survive IPaddress changes may continue to grow as 5G systems become increasinglywidespread.

Handover between the systems may be performed by using an LTE Attachprocedure or 5G equivalent. FIG. 6 illustrates handover with IP addresspreservation in accordance with some embodiments. FIG. 6 shows anon-roaming scenario of Network-Based IP Flow Mobility (NBIFOM)functionality. An example of a handover without IP address preservationis not shown for brevity. In either case, handover may be undertakenusing the UEs and eNBs shown in any of FIGS. 1-5.

If IP address preservation for a PDN connection is desired, handover forthat PDN connection may be performed using the Handover Attach procedureor its 5G equivalent, which allows the target access system to retrievethe already selected PGW whose address is stored in the HSS. FIG. 6illustrates a scenario in which handover occurs from a non-3GPP IPaccess to the E-UTRAN connected to the EPC. As shown, after determiningthat handover is appropriate, the UE 602 may send an Attach Request tothe MME 606 via the eNB 604. The Attach request may indicate withRequest Type indicating Handover Attach. The UE 602 may include anAccess Point Name (APN) corresponding to the PDN connections. The MME606 may contact the HSS 612 and authenticate the UE 602.

After successful authentication, the MME 606 may perform a locationupdate procedure and subscriber data retrieval from the HSS 612. Sincethe Request Type is Handover, the identity of the PGW 610 serving the UE602 may be stored in a PDN subscription context and conveyed to the MME606. The MME 606 may receive PDN information of the UE 602 in theSubscriber Data obtained from the HSS 612. The MME 606 may select anAPN, a SGW 608 and PGW 610 and send a Create Session Request message tothe selected SGW 608. The Create Session Request message may containHandover Indication information. The SGW 608 may then send a CreateSession Request message to the PGW 610 with the Handover Indicationinformation indicated by the MME 606.

The PGW 610 may execute a PCEF-Initiated IP CAN Session ModificationProcedure or a IP CAN Session Establishment with the PCRF depending onwhether the UE 602 disconnected from the default PDN before handover. Insome cases, dedicated bearers may be established for the UE 602. The PGW610 may send a Create Session Response message to the SGW 608. TheCreate Session Response may contain the IP address. The SGW 608 in turnsends a Create Session Response message to the MME 606. The CreateSession Response message also includes the IP address of the UE 602 andserves as an indication to the MME 606 that the S5 bearer setup andupdate has been successful—the PMIPv6 or GTP tunnel(s) over S5 may thusbe established.

The Radio and Access bearers may be established using RRC signalling.The MME 606 may send a Modify Bearer Request message to the SGW 608,which the SGW 608 may then send to the PGW 610 to initiate packetrouting to the SGW 608 for the default and any dedicated EPS bearersestablished. The PGW 610 may respond with a Modify Bearer Response tothe SGW 608, which the SGW 608 may then send to the MME 606. The UE 602may transmit and receive data.

In some embodiments, the EPC may be able to make a determination ofwhether to maintain the IP address during handover (and thus the samePGW is to be used) or whether a new IP address is to be used afterhandover (and thus a different PGW is to be used). This decision may bebased on various factors such as the type of UE (whether 5G capable ornot), the bearers established for the UE (which may be related to theapplications available for the UE or UE priority, among others), as wellas the functionality of the 5G and LTE eNBs. As indicated above, the IPflow mobility between the EPC-based access system and the 5G corenetwork-based access system may be based on a multi-access PDNconnection that is anchored in the common PGW.

FIG. 7 illustrates a flow diagram of handover in accordance with someembodiments. Handover may be undertaken using the UEs and cNBs shown inany of FIGS. 1-5. At operation 702, the UE may discover new cells anddetermine whether handover is appropriate. Handover may be based, forexample, on measured cell-specific reference signals (CRS) from thedifferent cells as well as UE mobility and other factors. The UE maymeasure the reference signal receive power (RSRP) and/or referencesignal receive quality (RSRQ), among others to make the determination.The UE may be able to operate in single mode or in dual mode, in thelatter of which the UE may be simultaneously attached to an EPC via anLTE cell (either directly or through a 5G booster cell) and to a 5G corenetwork via a standalone 5G cell. The mobility management mechanisms forthe access systems may be independent, permitting the U E to be in thesame or different modes for the different cells. In some embodiments,the UE can be simultaneously attached to both the EPC and 5G corenetwork without using the two RATs simultaneously.

At operation 704, the process 700 branches dependent on whether thehandover is an inter- or intra-RAT handover. In particular, if thehandover is between LTE cells or between 5G cells, at operation 706 thehandover process may use operations associated with either aconventional LTE handover or a 5G handover, as desired.

On the other hand, if the handover occurs between an LTE cell or 5G cellbooster cell anchored by a LTE cell and a 5G cell, at operation 708, itmay be determined whether a new IP address is to be assigned. The 5Gcell may either be a dual mode cell connected with both the EPC withwhich the LTE anchor cell is connected and the 5G core network, or a 5Gstandalone connected with the 5G core network but not the EPC.

If a new IP address is to be used, at operation 710, the UE sets ahandover flag in an Attach message. The Attach message is thentransmitted to the new cell. Whether or not a new IP address is to beused may depend on factors such as the UE type and capabilities.

At operation 712 handover is initiated. In situations in which a new IPaddress is used, the only point of commonality between the EPC and the5G core network may be the HSS, which contains the subscriberinformation for use in the new cell. In situations in which the originalIP address is retained, both the HSS and the PGW may serve as points ofcommonality between the EPC and the 5G core network, with the new cellusing the original PGW, which may serve as an IP anchor and whoseinformation is retrieved from the HSS during the handover procedure.

Examples

Example 1 is an apparatus of user equipment (UE), the apparatuscomprising: memory; and processing circuitry in communication with thememory and arranged to: determine whether the UE is configured forhandover between an evolved NodeB (eNB) connected with an evolved packetcore (EPC) of a Long Term Evolution (LTE) network and a base stationconnected with a 5th generation (5G) core network; determine whether toretain an internet protocol (IP) address associated with the LTE networkor 5G core network during handover; and in response to a determinationthat IP address retention is to occur, encode an Attach Request fortransmission to one of the eNB or the base station, the Attach Requestcomprising a Request Type that indicates a Handover Attach.

In Example 2, the subject matter of Example 1 optionally includes thatthe UE is attached to a 5G booster eNB connected with a LTE anchoreither prior to or after handover.

In Example 3, the subject matter of any one or more of Examples 1-2optionally include that the UE is attached to a 5G standalone eNB thatis connected with the 5G core network and is free from being connectedwith the EPC either prior to or after handover.

In Example 4, the subject matter of any one or more of Examples 1-3optionally include that the UE is attached to a 5G dual mode eNB that isconnected with the 5G core network and is connected with the EPC througha LTE anchor eNB either prior to or after handover.

In Example 5, the subject matter of any one or more of Examples 1-4optionally include, further comprising: a plurality of radios configuredto connect with different radio access technologies (RATs), the RATscomprising LTE and 5G, wherein the processing circuitry is furtherarranged to configure the UE to operate in dual mode in which the UE issimultaneously connected with the EPC and the 5G core network via thedifferent RATs.

In Example 6, the subject matter of Example 5 optionally includes thatthe processing circuitry is further arranged to: configure the UE tooperate in one of a Connected or Idle mode associated with each of theEPC and the 5G core network, the one of the Connected or Idle modeassociated with the EPC independent of the one of the Connected or Idlemode associated with the 5G core network.

In Example 7, the subject matter of any one or more of Examples 1-6optionally include that the processing circuitry is further arranged to:in response to a determination that a new IP address is to be assignedduring handover, cause the transceiver to transmit to one of the eNB orbase station an Attach Request comprising a Request Type that is freefrom an indication of a Handover Attach.

In Example 8, the subject matter of any one or more of Examples 1-7optionally include that the processing circuitry comprises a basebandprocessor, and the apparatus further comprises a transceiver configuredto communicate with the at least one of the eNB or base station.

Example 9 is an apparatus of a base station, the apparatus comprising: amemory: and processing circuitry in communication with the memory andarranged to decode from a user equipment (UE) an Attach Request thatcomprises a Request Type that is selectable by the UE between a HandoverAttach and a non-Handover Attach, the Handover Attach being anindication of Internet Protocol (IP) address retention during handover;and encode the Attach Request for transmission to a mobility managemententity (MME) to complete handover with the UE based on the AttachRequest.

In Example 10, the subject matter of Example 9 optionally includes thatan operation mode associated of the UE after completion of handover isindependent of an operation mode of the UE associated with another basestation to which the UE is simultaneously connected, the operation modecomprising one of a Connected or Idle mode.

In Example 11, the subject matter of any one or more of Examples 9-10optionally include that the base station is a 5G booster eNB connectedwith a LTE anchor.

In Example 12, the subject matter of any one or more of Examples 9-11optionally include that the base station is a 5G standalone eNB that isconnected with a 5G core network.

In Example 13, the subject matter of any one or more of Examples 9-12optionally include that the base station is a 5G dual mode eNB that isconnected with a 5G core network and is connected with an EPC through aLTE anchor eNB.

Example 14 is a computer-readable storage medium that storesinstructions for execution by one or more processors, the one or moreprocessors to: establish simultaneous operation between a user equipment(UE) and both a Long Term Evolution (LTE) access system and a 5thgeneration (5G) access system, the LTE access system comprising anevolved packet core (EPC), the 5G access system comprising a 5G corenetwork, wherein the UE is configured to operate in an LTE mobilitymanagement state and a 5G mobility management state, the LTE mobilitymanagement state and the 5G mobility management state independent ofeach other.

In Example 15, the subject matter of Example 14 optionally includes thatthe EPC and the 5G core network share a Home Subscriber Storage (HSS)node.

In Example 16, the subject matter of Example 15 optionally includes thatthe EPC and the 5G core network share an Internet Protocol (IP) anchor.

In Example 17, the subject matter of Example 16 optionally includes thatthe instructions further configure the one or more processors to: retainan IP address of the UE during handover of the UE between access systemsusing the IP anchor and the HSS in response to the UE using an AttachRequest comprising a Request Type that indicates a Handover Attach.

In Example 18, the subject matter of any one or more of Examples 16-17optionally include that the instructions further configure the one ormore processors to: assign a new IP address to the UE during handover ofthe UE between access systems using the IP anchor and the HSS inresponse to the UE using an Attach Request comprising a Request Typethat is free from an indication of a Handover Attach.

In Example 19, the subject matter of any one or more of Examples 14-18optionally include that the UE is connected with the EPC through a radioaccess network that uses a radio access technology selected from one of:General Packet Radio Services (GPRS), Universal MobileTelecommunications System (UMTS), a 4th generation (4G) system or anLTE-anchored 5G booster cell operating in Dual Connectivity mode.

In Example 20, the subject matter of any one or more of Examples 14-19optionally include that the UE is connected with the 5G core networkthrough a radio access network relying on a standalone 5G radio accesstechnology.

In Example 21, the subject matter of any one or more of Examples 14-20optionally include that the UE retains independent Packet Data Network(PDN) connections for each of the LTE and 5G access systems.

In Example 22, the subject matter of any one or more of Examples 14-21optionally include that the instructions further configure the one ormore processors to: provide a multi-access Packet Data Network (PDN)connection for the UE, the multi-access PDN connection having aconnection established with each of the LTE and 5G access systems withan Internet Protocol (IP) anchor that is common to both the LTE and 5Gaccess systems.

In Example 23, the subject matter of Example 22 optionally includes thatthe UE uses IP flow mobility (NBIFOM) mechanisms when handing over an IPflow from one of the LTE and 5G access systems to the other of the LTEand 5G access systems.

In Example 24, the subject matter of any one or more of Examples 14-23optionally include that at least one of: the UE is attached to a 5Gbooster eNB connected with a LTE anchor, the UE is attached to a 5Gstandalone eNB that is connected with the 5G core network and is freefrom being connected with the EPC, or the UE is attached to a 5G dualmode eNB that is connected with the 5G core network and is connectedwith the EPC through a LTE anchor eNB.

Example 25 is a method of providing a 5th generation (5G) access to auser equipment (UE), the method comprising: establishing simultaneousoperation between the UE and both a Long Term Evolution (LTE) accesssystem and a 5G access system, the LTE access system comprising anevolved packet core (EPC), the 5G access system comprising a 5G corenetwork; and configuring the UE to operate in an LTE mobility managementstate and a 5G mobility management state, the LTE mobility managementstate and the 5G mobility management state independent of each other.

In Example 26, the subject matter of Example 25 optionally includes thatthe EPC and the 5G core network share a Home Subscriber Storage (HSS)node.

In Example 27, the subject matter of Example 26 optionally includes thatthe EPC and the 5G core network share an Internet Protocol (IP) anchor.

In Example 28, the subject matter of Example 27 optionally includes,further comprising: retaining an IP address of the UE during handover ofthe UE between access systems using the IP anchor and the HSS inresponse to the UE using an Attach Request comprising a Request Typethat indicates a Handover Attach.

In Example 29, the subject matter of any one or more of Examples 27-28optionally include, further comprising: assigning a new IP address tothe UE during handover of the UE between access systems using the IPanchor and the HSS in response to the UE using an Attach Requestcomprising a Request Type that is free from an indication of a HandoverAttach.

In Example 30, the subject matter of any one or more of Examples 25-29optionally include that the UE is connected with the EPC through a radioaccess network that uses a radio access technology selected from one of:General Packet Radio Services (GPRS), Universal MobileTelecommunications System (UMTS), a 4th generation (4G) system or anLTE-anchored 5G booster cell operating in Dual Connectivity mode.

In Example 31, the subject matter of any one or more of Examples 25-30optionally include that the UE is connected with the 5G core networkthrough a radio access network relying on a standalone 5G radio accesstechnology.

In Example 32, the subject matter of any one or more of Examples 25-31optionally include that the UE retains independent Packet Data Network(PDN) connections for each of the LTE and 5G access systems.

In Example 33, the subject matter of any one or more of Examples 25-32optionally include, further comprising: providing a multi-access PacketData Network (PDN) connection for the UE, the multi-access PDNconnection having a connection established with each of the LTE and 5Gaccess systems with an Internet Protocol (IP) anchor that is common toboth the LTE and 5G access systems.

In Example 34, the subject matter of Example 33 optionally includes thatthe UE uses IP flow mobility (NBIFOM) mechanisms when handing over an IPflow from one of the LTE and 5G access systems to the other of the LTEand 5G access systems.

In Example 35, the subject matter of any one or more of Examples 25-34optionally include that at least one of: the UE is attached to a 5Gbooster eNB connected with a LTE anchor, the UE is attached to a 5Gstandalone eNB that is connected with the 5G core network and is freefrom being connected with the EPC, or the UE is attached to a 5G dualmode eNB that is connected with the 5G core network and is connectedwith the EPC through a LTE anchor eNB.

Example 36 is an apparatus of a user equipment (UE), the apparatuscomprising: means for establishing simultaneous operation between the UEand both a Long Term Evolution (LTE) access system and a 5th generation(5G) access system, the LTE access system comprising an evolved packetcore (EPC), the 5G access system comprising a 5G core network: and meansfor configuring the UE to operate in an LTE mobility management stateand a 5G mobility management state, the LTE mobility management stateand the 5G mobility management state independent of each other.

In Example 37, the subject matter of Example 36 optionally includes thatthe EPC and the 5G core network share a Home Subscriber Storage (HSS)node.

In Example 38, the subject matter of Example 37 optionally includes thatthe EPC and the 5G core network share an Internet Protocol (IP) anchor.

In Example 39, the subject matter of Example 38 optionally includes,further comprising: means for retaining an IP address of the UE duringhandover of the UE between access systems using the IP anchor and theHSS in response to the UE using an Attach Request comprising a RequestType that indicates a Handover Attach.

In Example 40, the subject matter of any one or more of Examples 38-39optionally include, further comprising: means for assigning a new IPaddress to the UE during handover of the UE between access systems usingthe IP anchor and the HSS in response to the UE using an Attach Requestcomprising a Request Type that is free from an indication of a HandoverAttach.

In Example 41, the subject matter of any one or more of Examples 36-40optionally include that the UE is connected with the EPC through a radioaccess network that uses a radio access technology selected from one of:General Packet Radio Services (GPRS), Universal MobileTelecommunications System (UMTS), a 4th generation (4G) system or anLTE-anchored 5G booster cell operating in Dual Connectivity mode.

In Example 42, the subject matter of any one or more of Examples 36-41optionally include that the UE is connected with the 5G core networkthrough a radio access network relying on a standalone 5G radio accesstechnology.

In Example 43, the subject matter of any one or more of Examples 36-42optionally include that the UE retains independent Packet Data Network(PDN) connections for each of the LTE and 5G access systems.

In Example 44, the subject matter of any one or more of Examples 36-43optionally include, further comprising: means for providing amulti-access Packet Data Network (PDN) connection for the UE, themulti-access PDN connection having a connection established with each ofthe LTE and 5G access systems with an Internet Protocol (IP) anchor thatis common to both the LTE and 5G access systems.

In Example 45, the subject matter of Example 44 optionally includes thatthe UE uses IP flow mobility (NBIFOM) mechanisms when handing over an IPflow from one of the LTE and 5G access systems to the other of the LTEand 5G access systems.

In Example 46, the subject matter of any one or more of Examples 36-45optionally include that at least one of: the UE is attached to a 5Gbooster eNB connected with a LTE anchor, the UE is attached to a 5Gstandalone eNB that is connected with the 5G core network and is freefrom being connected with the EPC, or the UE is attached to a 5G dualmode eNB that is connected with the 5G core network and is connectedwith the EPC through a LTE anchor eNB.

Although an embodiment has been described with reference to specificexample embodiments, it will be evident that various modifications andchanges may be made to these embodiments without departing from thebroader scope of the present disclosure. Accordingly, the specificationand drawings are to be regarded in an illustrative rather than arestrictive sense. The accompanying drawings that form a part hereofshow, by way of illustration, and not of limitation, specificembodiments in which the subject matter may be practiced. Theembodiments illustrated are described in sufficient detail to enablethose skilled in the art to practice the teachings disclosed herein.Other embodiments may be utilized and derived therefrom, such thatstructural and logical substitutions and changes may be made withoutdeparting from the scope of this disclosure. This Detailed Description,therefore, is not to be taken in a limiting sense, and the scope ofvarious embodiments is defined only by the appended claims, along withthe full range of equivalents to which such claims are entitled.

The subject matter may be referred to herein, individually and/orcollectively, by the term “embodiment” merely for convenience andwithout intending to voluntarily limit the scope of this application toany single inventive concept if more than one is in fact disclosed.Thus, although specific embodiments have been illustrated and describedherein, it should be appreciated that any arrangement calculated toachieve the same purpose may be substituted for the specific embodimentsshown. This disclosure is intended to cover any and all adaptations orvariations of various embodiments. Combinations of the aboveembodiments, and other embodiments not specifically described herein,will be apparent to those of skill in the art upon reviewing the abovedescription.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one, independent of any otherinstances or usages of“at least one” or “one or more.” In this document,the term “or” is used to refer to a nonexclusive or, such that “A or B”includes “A but not B,” “B but not A,” and “A and B,” unless otherwiseindicated. In this document, the terms “including” and “in which” areused as the plain-English equivalents of the respective terms“comprising” and “wherein.” Also, in the following claims, the terms“including” and “comprising” are open-ended, that is, a system, UE,article, composition, formulation, or process that includes elements inaddition to those listed after such a term in a claim are still deemedto fall within the scope of that claim. Moreover, in the followingclaims, the terms “first,” “second,” and “third,” etc. are used merelyas labels, and are not intended to impose numerical requirements ontheir objects.

The Abstract of the Disclosure is provided to comply with 37 C.F.R. §1.72(b), requiring an abstract that will allow the reader to quicklyascertain the nature of the technical disclosure. It is submitted withthe understanding that it will not be used to interpret or limit thescope or meaning of the claims. In addition, in the foregoing DetailedDescription, it can be seen that various features are grouped togetherin a single embodiment for the purpose of streamlining the disclosure.This method of disclosure is not to be interpreted as reflecting anintention that the claimed embodiments require more features than areexpressly recited in each claim. Rather, as the following claimsreflect, inventive subject matter lies in less than all features of asingle disclosed embodiment. Thus the following claims are herebyincorporated into the Detailed Description, with each claim standing onits own as a separate embodiment.

1-24. (canceled)
 25. An apparatus of user equipment (UE), the apparatuscomprising: memory; and processing circuitry in communication with thememory and arranged to: determine whether the UE is configured forhandover between a first base station associated with a first networkcore and a second base station associated with a second network core,wherein the first base station corresponds to a first radio accesstechnology (RAT), wherein the second base station corresponds to asecond RAT different from the first RAT; determine whether to retain aninternet protocol (IP) address associated with the first network core orthe second network core during handover; and in response to adetermination that IP address retention is to occur, transmit to thefirst base station or the second base station a message to establish aconnection, the message comprising a request type that indicates thatthe connection is to be established as part of a handover.
 26. Theapparatus of claim 25, wherein the second base station is a boosternode, wherein the first base station is an anchor node relative to theUE.
 27. The apparatus of claim 25, wherein the UE is connected to thesecond base station either before or after handover, wherein the secondbase station is a 5G standalone node, wherein the UE is free from beingconnected to the first network core either after or before the handover.28. The apparatus of claim 25, wherein the second base station is a 5Gdual mode base station.
 29. The apparatus of claim 25, furthercomprising a plurality of radios configured according to different RATs,including the first RAT and the second RAT; wherein the processingcircuitry is further arranged to configure the UE to operate in a dualmode in which the UE is simultaneously connected with the first basestation and the second base station.
 30. The apparatus of claim 25,wherein the processing circuitry is further arranged to: configure theUE to operate in one of a connected or idle mode with respect to thefirst network core; and independently configure the UE to operate in oneof a connected or idle more with respect to the second network core. 31.The apparatus of claim 25, wherein the processing circuitry is furtherarranged to: in response to a determination that a new IP address is tobe assigned during handover, cause a transceiver of the UE to transmitto one of the first base station or the second base station a secondmessage comprising a request type that is free from an indication ofhandover.
 32. The apparatus of claim 25, wherein the processingcircuitry comprises a baseband processor, wherein the apparatus furthercomprises a transceiver configured to communicate with the at least oneof the first base station or the second base station.
 33. An apparatusof a mobility management node, the apparatus comprising: a memory; andprocessing circuitry in communication with the memory and arranged to:receive, from a UE, from a user equipment (UE), a connectionestablishment message, wherein the message is received via a firstnetwork core associated with a first base station or via a secondnetwork core associated with a second base station, wherein the firstbase station and the second base station corresponding respective to afirst radio access technology (RAT) and a second RAT, wherein themessage comprises a request Type that is selectable by the UE, whereinrequest type is set to a type that is indicative of a connection to behanded over with Internet Protocol (IP) address retention during thehandover; perform handover according to the request type.
 34. Theapparatus of claim 33, wherein the first network core is an EvolvedPacket Core (EPC) of 3GPP LTE.
 35. The apparatus of claim 33, whereinthe second network core is a 5G core network.
 36. The apparatus of claim33, wherein the first RAT is 3GPP LTE, wherein the second RAT is 5G NR.37. The apparatus of claim 33, wherein the second base station is a 5Gstandalone base station or a 5G dual mode base station.
 38. A method foroperating a user equipment (UE), the method comprising: determiningwhether the UE is configured for handover between a first base stationassociated with a first network core and a second base stationassociated with a second network core, wherein the first base stationcorresponds to a first radio access technology (RAT), wherein the secondbase station corresponds to a second RAT different from the first RAT;determining whether to retain an internet protocol (IP) addressassociated with the first network core or the second network core duringhandover; and in response to a determination that IP address retentionis to occur, transmitting to the first base station or the second basestation a message to establish a connection, the message indicating thatthe connection is to be established as part of a handover.
 39. Themethod of claim 38, wherein a packet data network (PDN) connection ismoved the second RAT as part of the handover.
 40. The method of claim38, wherein the first network core is an Evolved Packet Core (EPC) of3GPP LTE, wherein the second network core is a 5G core network, whereinthe first RAT is 3GPP LTE, and wherein the second RAT is 5G NR.
 41. Themethod of claim 38, wherein the first network core is a 5G core network,wherein the second network core is an Evolved Packet Core (EPC) of 3GPPLTE, wherein the first RAT is 5G NR, and wherein the second RAT is 3GPPLTE.
 42. The method of claim 38, wherein the UE is connected to thesecond base station either before or after handover, wherein the secondbase station is a 5G standalone node, wherein the UE is free from beingconnected to the first network core either after or before the handover.43. The method of claim 38, further comprising: configuring the UE tooperate in a dual mode in which the UE is simultaneously connected withthe first base station and the second base station.
 44. The method ofclaim 38, further comprising: configure the UE to operate in one of aconnected or idle mode with respect to the first network core; andindependently configure the UE to operate in one of a connected or idlemore with respect to the second network core.